Epstein-Barr virus (EBV) has the capacity to transform human B lymphocytes into continuously proliferating lymphoblastoid cell lines. This virus is also responsible for several lymphoproliferative disorders of B cell origin. Despite accumulating knowledge about the virus itself and its receptor on the surface of human B cells, little is known about the ionic, biochemical or molecular/genetic events which follow EBV binding to the cells or the early events involved in infection and transformation of the cells. This is in contrast to what has been learned about B-cell activation following receptor binding by other ligands which induce B cells to proliferate. In this proposal we will compare the responses of resting and activated B cells to EBV and other ligands. We will monitor the earliest documented changes in ion transport using a series of fluorescent probes to assay changes in cytosolic calcium concentrations, cytosolic pH and membrane potential. To monitor subsequent or intermediate events, we will follow the induction of specific mRNAs for the cell-cycle activation genes including c-fos, c-myc, EGR1, interleukin 2 and the interleukin 2 and transferrin receptors. These studies will then be correlated with the later events including DNA synthesis and Ig secretion as well as frequency of transformation assessed in a limiting dilution assay. In the four specific aims we will a) examine and compare the consequences of EBV binding on freshly isolated, resting B cells to other known B cell mitogens, b) characterize and compare early activation events that occur when in vitro EBV-transformed cell lines and Burkitt's lymphoma cell lines are stimulated with different ligands and EBV, c) determine if stimulation of second messenger pathways modulates EBV function and d) determine the effect of preactivation of B cells by specific ligands on the transformation ability of EBV. The data accumulated during the course of this proposal will provide new and important information about this novel activation pathway and, hopefully, clearer insight into the potential regulation of the uncontrolled B-cell lymphoproliferation induced by this virus.